pjs/grendel/calypso/util/Recycler.java

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5.4 KiB
Java
Исходник Обычный вид История

1998-09-09 04:52:38 +04:00
/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil -*-
*
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* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
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*
* The Original Code is the Grendel mail/news client.
*
* The Initial Developer of the Original Code is Netscape Communications
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* Corporation. Portions created by Netscape are
* Copyright (C) 1997 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
1998-09-09 04:52:38 +04:00
*/
package calypso.util;
import java.util.*;
/**
*
*
* @author gess 04-16-97 1:44pm
1999-11-02 04:51:54 +03:00
* @version $Revision: 1.2 $
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* @notes This is a general purpose recycler.
* It contains objects of a specified capacity.
* If you ask for a recycled object and we have
* one, then it's returned as object as you must typecast.
* If we don't have a recycled object, we return null.
*/
public class Recycler implements MemoryPressure
{
Object[] fBuffer;
int fCount;
int fCapacity;
final static int gDefaultCapacity = 100;
/******************************************
* @author gess 04-16-97 1:40pm
* @param
* @return
* @notes default constructor, assumes
buffer capacity of 100
*******************************************/
public Recycler()
{
MemoryManager.Add(this);
fCapacity=gDefaultCapacity;
reset();
}
/********************************************************
* @author gess 04-16-97 1:40pm
* @param aGivenCapacity -- size of underlying buffer
* @return
* @notes constructor with capacity argument
********************************************************/
public Recycler(int aGivenCapacity)
{
MemoryManager.Add(this);
fCapacity=aGivenCapacity;
reset();
}
/********************************************************
* @author gess 04-16-97 1:43pm
* @param none
* @return none
* @notes discards original buffer (if present) and creates
a new buffer of size fCapacity
*********************************************************/
public void reset()
{
fBuffer= new Object[fCapacity];
fCount = 0;
}
/********************************************************
* @author gess 04-16-97 1:43pm
* @param anObject -- object to be recycled
* @return none
* @notes always drop on end of list; when capacity is
reached, replaced last entry
*********************************************************/
public void recycle(Object anObject)
{
if (null!=anObject)
{
if (null==fBuffer)
{
reset();
fBuffer[fCount++] = anObject;
}
else
{
if (fCount==fCapacity)
{
// Replace last entry with the new one,
// to improve memory locality
fBuffer[fCount-1] = anObject;
}
else
fBuffer[fCount++] = anObject;
}
}
}
/**
* Recycles the entire contents of the given list.
*
* @param
* @return
* @exception
* @author gess 04-16-97 4:22pm
**/
public void recycle(Object anObjectArray[])
{
int count = anObjectArray.length;
int index;
for (index = 0; index < count; index++)
{
recycle (anObjectArray[index]);
anObjectArray[index] = null;
}
}
/********************************************************
* @author gess 04-16-97 1:43pm
* @param none
* @return object or null
* @notes if we don't have any recycled objects, we
return null. Objects we DO return must be
type cast by you to the appropriate type.
*********************************************************/
public Object getRecycledObject()
{
Object result=null;
if (fCount>0)
{
result=fBuffer[--fCount];
fBuffer[fCount]=null;
}
return result;
}
/******************************************
* @author gess 04-16-97 1:40pm
* @param none
* @return none
* @notes causes buffer to be released and
count to be reset to 0.
*******************************************/
public void empty()
{
fCount = 0;
fBuffer = null;
}
/******************************************
* @author gess 04-16-97 1:40pm
* @param
* @return
* @notes copied from kipps implementation
*******************************************/
public void preGC(long aCurrentHeapSpace, long aMaximumHeapSpace)
{
// Discard our array of buffers so that the GC can
// compact the heap nicely.
empty();
}
/******************************************
* @author gess 04-16-97 1:41pm
* @param
* @return
* @notes copied from kipps implementation
*******************************************/
public void postGC(long aCurrentHeapSpace, long aMaximumHeapSpace)
{
}
/******************************************
* @author gess 04-16-97 1:40pm
* @param
* @return
* @notes
*******************************************/
public void panic()
{
// Get rid of everything, including ourselves
empty();
}
}